1. Field of the Invention
The present invention relates to method of calculating pattern-failure-occurrence-region, a computer program product, a pattern-layout evaluating method, and a semiconductor-device manufacturing method.
2. Description of the Related Art
In a lithography process in manufacturing a semiconductor device, after thin organic films such as a processed film, a resist, and a protective film are applied and formed on a wafer substrate, the resist and the protective film are exposed to light and developed to form a resist pattern. In the lithography process, the wafer substrate to which the resist is applied is not always flat depending on a process. For example, when a gate is already formed on the wafer substrate, a step (convex) is formed on the wafer substrate because of a convex shape of a gate electrode formed of polysilicon or the like. In the lithography process, the resist may be applied to the wafer substrate having the step.
In such a lithography process performed when the wafer substrate has the step, a dimension difference due to an exposure failure may occur in a pattern formed by an upper part of the step and a lower part of the step and cause a pattern formation failure. To eliminate such a pattern formation failure, it is necessary to extract a hot spot in a process from a pattern layout and correct the pattern layout or correct a photomask as required.
For example, in a mask pattern correcting method disclosed in Japanese Patent Application Laid-Open No. 2006-276491, a design mask pattern of a target layer and a step pattern formed in a layer under the target layer are extracted, a plurality of intersections where a transfer image of the design mask pattern and the step pattern cross are detected, and intersection distances among the intersections are calculated. In each of the intersections, a first treatment region including the intersection is set on an arrangement surface of the design mask pattern based on the intersection distances. A first transfer image of the design mask pattern transferred in the first treatment region is calculated based on the step pattern. The design mask pattern is corrected based on the first transfer image.
However, this correcting method is a method of extracting a region right above a step and correcting a mask pattern. When a hot spot occurs in a region other than the region right above the step, a position of the hot spot cannot be specified.